It didn’t take long after we originally tuned Sam’s 2012 Black Edition GTR on 91 octane and E85 that we upgraded turbos. An oil leak on the passenger side turbo oil feed line helped that decision! Bigger turbos on a stock motor! An option that actually works very well when performed properly. The stock turbos are small and lose their efficiency at the higher RPMs. They have trouble holding boost and terrible back pressure ensues.

With the engine out we went to work pulling off the stock turbos and finding the culprit for the oil leak.

The stock turbos before they go in for surgery.

The passenger side turbo oil feed line pictured above. This portion of the line bolts to the top of the turbo with a banjo bolt and crush washer. If you look closely you can see the red arrow pointing to the crack in the brazing of where the line meets the banjo fitting. This is somewhat of a common issue. Nissan has an updated part for both the oil line and a bracket (2014+).

The “old” bracket on the left and the new on the right. You can see that the new bracket has an additional provision to support the oil feed line. The new line has an additional winglet to bolt to the new bracket.

Our turbo upgrade came from RD Engineering. The anodized blue wheel on the left is the upgraded compressor wheel and the factory GTR compressor wheel on the right. A rather large difference!

Turbine wheel also gets upgraded to help decrease that pesky back pressure.

The only other upgrade performed while we were in there were GTC Turbo Inlets. GTC on the left and the factory DBA inlet on the right which is already larger from the CBA (2009-2011) models.

The upgraded turbos feature Turbosmart actuators.

Above is the 91 octane dyno graph differences. Sam’s GTR has basic bolt-ons so the results can be better with modifications like an upgraded intercooler, intercooler piping, etc.. Blue was the power on stock turbos. Red is the upgraded turbos. This upgrade essentially allows one to run E85 FBO stock turbo power levels on 91 octane. A nice upgrade indeed if you don’t have E85 easily accessible. By 3500 RPMs the larger turbos start to take over on the stock motor and cams. As mentioned previously, more “breather mods” can help this. We’re also forced to limit our torque output with the stock connecting rods.

Our E85 dyno graph. Blue is stock turbos (please excuse the RPM cut) and red our upgraded turbos. Again we are having to severely limit our torque output on E85. The potential with these turbos on a forged motor is much more. One can see that the stock turbos hit rather hard in the beginning. If you look at our cursor pointing at 6500 RPMs you can see how much the stock turbos fall off on boost where the larger turbos shine. This is a reminder that upgrading actuators on the stock turbos is not recommended. Your only increasing your back pressures which are horrendous for the engine. Close to 800 whp on a stock engine and still able to keep the torque level in check which is the achilles heel of the factory GTR shortblock.

I’ll start off by sincerely apologizing for not staying up with the blog. The shop is super busy and my personal life is much busier with the addition of a second child. We recently had the pleasure of testing the Tomei Expreme Ti exhaust for the R35 GTR. Our test GTR has the following modifications performed:

SZ Built Motor (stock camshafts & stock heads)

USM Turbos

SZ 3″ Intake

Factory Intercooler & Piping

AMS Down Pipes

Fast Intentions Y-Pipe (Mil Spec Cats & Resonator) 3.5″

3″ Aftermarket Catback

The system includes its own y-pipe using 3″ piping coming out of each down pipe outlet merging into the single 4″ pipe. The quality and fitment of the Tomei system is spectacular. Nothing had to be cut or hacked up to make the fitment of the 4″ piping go through the diffusers. Considering the system is made of titanium the MSRP of $3600 is a steal! The weight savings over a conventional SS system is amazing. Tomei says its a 35 lb savings over the factory pieces with the Tomei system weighing in at 32 lbs which includes the y-pipe.

Y-pipe dual 3″ from the down pipes into the massive 4″ sewer pipe.

The system snakes its way perfectly through the diffusers without any problems. No trimming, no modifying. The welds on the titanium are beautiful for a mass produced system.

Straight thru “mufflers”.

The view from right above the carbon diffuser.

Everything exits out the huge 5.1″ tips.

Dyno test before and after done within a few hours of each other. Blue is the old exhaust setup and red is the after with the Tomei system. The largest gains were below 4500 RPMs. At 4k we gained 60 torque and 46 whp. You can see the boost pressure go up due to the exhaust change. We expected to see larger gains at the top than we did but we won’t complain about 20-25 whp gains.

Tony came back after upgrading to 3″ intakes, Bosch 1300cc fuel injectors, Walbro 485 fuel pump (secondary), and a Fast Intentions catback. Y-pipe has been swapped out for one with high flow cats to keep smell down as well. His previous visit here.

With the addition of the new mods and tuning we were able to extract more power on 91 octane. Over 55 whp and 80 torque gains were realized.

This exquisite example of a GTR came in by way looking for more power. We were here to help make that possible. Already equipped with a 5Zigen catback and an off the self Cobb tune we proceeded to go to work.

First thing’s first. The 2012+ GTRs came from the factory with larger turbo inlet pipes. We took the opportunity to port the 2012 inlet pipe to better match the factory turbo inlet opening (pictured on the right). You can see the huge difference on the left side. Driver side turbo pipes.

Passenger side turbo inlets. 2009-2011 pipe on the left and our ported 2012+ pipe on the right.

Our passenger side turbo playing peekaboo!

Driver side

After the larger inlets were installed, a SZ 3″ intake was also installed.

Larger 1100cc fuel injectors installed into the factory fuel rail so we can run ethanol.

Secondary pump was upgraded with a Walbro “485”.

It’s very hard to see in this picture, but right behind the intake manifold we installed our own flex fuel sensor kit. We went after a factory look, no one would know any better that this GTR came factory a flex fuel vehicle. Using EcuTek, we can modify the factory Nissan ECU to also perform flex fuel duties. The sensor reports back to the ECU and the appropriate changes are made to run on any mixture of gasoline and ethanol!

Driver side turbo (turbine) ready for the real AMS 3.5″ down pipe.

The down pipes installed.

Our first SZ\FI Open Y-Pipe with flex joints.

Ready for action! Now that its ready for flex fuel we tuned on 91 octane then switched to E85, followed by different mixtures.

Our results on our wonderful 91 octane fuel.

E85 tune. We dialed this monster back too! We could have easily hit 700 torque and 660 whp.

A GTR dressed in red is very sexy. Aided by SSR wheels and carbon fiber bits.

We previously installed down pipes on Mark’s GTR some time ago (click me to see the old blog post). Mark came back in for a few tweaks. One was to make the move to EcuTek from Cobb. Since Mark is an avid drag racer, EcuTek gives him the ability to make on the fly changes to his launching RPMs. If the track isn’t prepped as well as he’d like he can lower the launch control RPM for better 60 foots along with raising the RPM should the track and tires hold it. Changes to launch control boost pressures can also be made. We also made the move to allow his GTR to run on ethanol.

The first order of business was upgrading the fuel injectors to allow more fuel for ethanol use. We went with 1150cc fuel injectors and necessary adapter kit for a simple plug n’ play solution. Injectors are installed in the above picture.

Factory fuel injector on the left and our 1150cc injector on the right.

We upgraded the secondary fuel pump with a Walbro “485” fuel pump. We noticed that the pump socks off the 2012s are much smaller than the ones off of the 2014s. Small changes Nissan makes throughout the years.

The factory air boxes (one pictured above) was removed and replaced with open air element filters and larger 3″ piping. This change allows us to continue running MAF sensors since now the threshold for maxing out the sensors has been moved up. Tuned on 91 octane will get you extremely close to maxing out the factory MAF sensors. Thankfully with EcuTek we can ditch the MAF sensors and convert to speed density. Perfect for someone not wanting to upgrade to an aftermarket intake(s) or for those with larger upgraded turbos.

Our new 3″ intakes installed. You can see the air filters get moved up to the bumper area keeping them away from the engine bay and its heat. The cover for the top of the bumper is removed to show where the filters now sit. The intake piping is hard to notice since it is powdercoated wrinkle black and we’ve acquired more “open” space with the removal of the air boxes.

Final shot of the install.

After all the modifications were completed we tuned for 91 octane. Making peak power on 14 psi. Boost drops off at the top due to turbo sizing. There are a few things that can be done to help make the stock turbos hold more but in doing so back pressure rises quickly between the engine and turbines.

Tony’s GTR came to us with just an aftermarket Y-Pipe and stock tuning from the factory.

We went to work armed with EcuTek software to make this GTR run properly on 91 CA fuel. Stock GTR tuning is meant for a minimum of 93 octane here in the States.

The blue run was the baseline stock tune and red is the new tuned run. We gained a nice 60 whp and torque throughout most of the low to mid range RPMs. Now with the EcuTek RaceRom features Tony can control boost via the steering wheel controls and have access to different maps on the fly. Plans are in the works to upgrade fuel injectors, secondary fuel pump so we can run ethanol fuel with our upcoming flex fuel kit for the GTRs.

Since we’ve become an ECUTek tuner we now have the ability to play with the GTR. Enter the following 2014 GTR.

The 3rd Gen R35 GTR, each year is better and better with improved refinements top to bottom.

The goal for this GTR this time around was to get it tuned properly for 91 octane as the GTR is meant for a minimum of 93 octane from the factory. Knock is high on our wonderful 91 octane fuel so things needed to change in the tune. Besides tuning for 91 octane we also went to work by upgrading this GTR to run ethanol fuel. We upgraded to 1300cc fuel injectors and also replaced the secondary fuel pump to a Walbro 485 pump. We were interested in seeing what a bone stock GTR with a tune for both 91 octane fuel and ethanol would do.

Ready for the injector swap.

Our 1300cc fuel injectors.

Factory fuel pump assembly that houses the twin pumps.

Stock pumps sitting together, we installed a single Walbro 485 to replace the secondary pump. Since one Walbro can support 600whp on ethanol we felt leaving the primary pump stock more than adequate for stock turbo power levels.

Baseline on the stock tune and stock fuel injectors.

Tuned on 91 octane tweaking boost, AFRs, and timing to make it happy and not knock (on the new 1300cc fuel injectors)

Tune on ethanol for impressive gains. All on a bone stock GTR (other than injectors, pump, and tune).

All 3 runs plotted together to show the differences. Next up, exhaust mods!

SZ is now an EcuTek Tuner for the 370Z\G37 & GTR. EcuTek provides far superior abilities in tuning the factory Nissan ECUs than other current tuning software. Maps that are not accessible by these other tuning suits can now be done so as well as the addition of custom maps to the existing factory Nissan ECU.

The ProECU Programming Kit can be used by car enthusiasts and owner clubs to both diagnose and program a wide variety of vehicles. Purchasing the kit is not required to those coming to us for a tune. The kits are available through a master tuner if needed for remote tuning purposes or ROM support.

370Z & G37 tuning support with the addition of EcuTek’s RaceRom features allows us to use a more simplified ignition timing strategy to have full control of timing while keeping all the safeguards of the knock control system. Another big plus is the ability to have E85 fuel & ignition compensation with the addition of a flex fuel sensor.

RaceROM is a suite of feature enhancements available for OEM ECUs tuned with EcuTek tuning tools, which offers increased tuning & driving capabilities.

Without question, the OEM ECU offers the best cold start, drive-ability and refinement when compared to aftermarket ECU hardware. However, many aftermarket ECUs provide extra (generally motorsport related) features, that many enthusiasts desire. Unfortunately, when replacing the standard ECU with an aftermarket ECU, the refinement of the standard ECU is often lost.

Now with EcuTek RaceROM, this compromise is no longer necessary. By way of a software upgrade to the standard ECU, RaceROM adds many custom calibration options to the standard OEM ECU, offering features beyond the standard fueling, ignition and boost control, yet retaining its drive-ability, sophistication and fuel economy.

Note that due to technical limitations of some ECUs, it is not possible to provide all features on all vehicles.

The GTR tuning suite allows full control over all aspects of the ECU and the addition of RaceROM features like boost control, launch control tuning, map switching, visual knock warning, flex fuel, and conversion to speed density (MAP), and much more.